Presuming that Whitney is searching for Rainsford, who has succeeded in slaying Zaroff in the duel of the bed chamber, and is still sailing in the waters near Ship-Trap Island, Rainsford must first figure out how to get a message to him. One option is to use the ploy of General Zaroff to draw ships near--the use of the lights indicating a false channel. But, he would have to warn ships before they entered into the rocks by the lights, else they would shipwreck. In the case that he can stop a ship, he would need, then, to find one that could meet the ship manned by the Swede with Whitney on board and pass on a message. Otherwise, he must rely on one of the sailors who are imprisoned in the cellar. After he frees them, one of them can carry the message in the hopes that a ship which picks him up will encounter Whitney's. (Also, there must be ships that bring various supplies to the island.)
In his letter to Whitney, Rainsford must explain that he leaped upon the rail of the vessel when he had heard a gun fire three times; however, when his pipe fell from his mouth, he lunged for it and fell into the dark waters. When he could not regain the yacht, he swam towards the sound of the shots, and barely made it onto shore. In utter exhaustion, he fell asleep, only waking in the afternoon of the following day. Figuring that pistol shots meant men must be around, he set out along the shore since there was no trail. Soon he found footprints and followed them until dark; then he saw lights. Finally, he was confronted by a huge man with a black beard to his waist, a man he learned later had no tongue and was called Ivan. Ivan pointed a revolver at Rainsford and had him walk to a chateau where a General Zaroff lived, another Russian.
He was taken to a room, given evening clothes, and fed a Russian dinner. But, at this meal, Rainsford learned that the sadistic and bored hunter, General Zaroff, sought more interesting game: humans. Rainsford asked to leave, but the general informed him he must hunt. Rainsford was sent out into the night; he ran and doubled back, then he climbed a tree, only to look down and see Zaroff. "Whitney," Rainsford writes, "I knew then the terror of the jaguar that you spoke of. I was being hunted like a beast!" The next day, he set a couple of traps, a dog was impaled in one and Ivan was killed, Rainsford was chased like an animal until he jumped off a cliff, but the general returned to his chateau to rest for the night, hoping to resume the hunt the next day.
(Be sure to word Rainsford's account in the first person and change the tense to present as it is in the last section below)
Rainsford can end his letter in this way:
Whitney, I knew then how a beast at bay felt! You were right. I swam, then I climbed the rocks and the sea wall up to the chateau until I reached the general's chamber and climbed in the window, hiding behind the bed curtains until he entered after his supper. We fought a duel; I won. Now, no one is here but me and the other prisoners.
Please rescue me. I have sent messages with these other sailors, some of whom have made contact with ships. I hope one of these reaches you because I have been wounded and am too weak to travel with any of those other men.